whats your favorite crowning tool

I want a healthy discount!! LOL!!!

I was talking with a good friend of mine today and he was telling me that PT&G has breach cone cutting tools. This sounds really appealing to me. He says they are good tools especially for a beginner like myself. he single points everything now so he may sell them to me. i was just curious if anyone here uses these tools? I am going to build a cylinder type tool with a dial gauge .001 in the top with a spring and a cone slug inside so i can take readings from barrels i already have, and i can use this tool to check the cone on the barrel thats in the lathe. I think this will be a good way to duplicate the cone cut from one barrel to the next?
I still haven't decided on a tool for cutting crowns yet. To be boldly honest when i look on a web site or in the catalog i dont always know what i am looking at yet. I read a lot though and i am slowly educating myself. I will get there! Thanks guys. Lee
 
JerrySharrett said:
Something many new gunsmiths don't realize, your half-nut and thread screw contains a lot of "slop". Feeding straight in, you may not be cutting a constant pitch thread. Setting the compound on 29.5 only one side of the threading tool is actually removing metal. The other side is creating a back-load that keeps the slack in that half-nut/lead-screw going in the same direction.

What this means, simply, your threaded joint (tenon) will not be making full contact throughout the entire assembly.
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Jerry,

I did not know the above. Thanks for sharing it.

I've never tried threading with the compound as I have never figgered' out how to "kick out" at the same point everytime.

As far as the threaded joint fit not making full contact, do you think that is going to have any effect on the rifle/accuracy/etc? My understanding is that there isn't much, if any stress put on those threads due to firing. They just hold barrel and action together, so thread fit is not super critical.

Your thoughts?

Justin
 
Dave Manson makes small caliber specific reamers to be used with removable bushings that will ream a perfect 45* crown at the bore/muzzle point. It's impossible to get a bad crown when using these reamers correctly.

They were designed to remove swarf and crown the barrel when a muzzle brake is an integral part of the barrel. I just started touching up the crown with them because they worked so well.
 
Zebra13 said:
Jerry,

I did not know the above. Thanks for sharing it.

I've never tried threading with the compound as I have never figgered' out how to "kick out" at the same point every time.

Use a felt tip pin and make a mark on the way up against the left carriage wing with the tool where you want it to stop. Then instead of watching the tool as it spits and smokes just watch that mark. Practice this a few times with the tool backed off to get the feel or it.

As far as the threaded joint fit not making full contact, do you think that is going to have any effect on the rifle/accuracy/etc? My understanding is that there isn't much, if any stress put on those threads due to firing. They just hold barrel and action together, so thread fit is not super critical. Oh yes it is. I know one of the top gunsmiths that even lap the threads into the action to get an even loading in the torqued joint. I don't think this is over-kill and it will eventually ear the action threads.

Your thoughts?

Justin
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Thats it..(I had to type something outside the quotes to get this to post.)
 
JerrySharrett said:
Thats it..(I had to type something outside the quotes to get this to post.)
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Jerry,

I do that exact thing. A little Sharpie mark on the ways...I find it easier than using an indicator. But if your feeding in with the compound, your tool is moving in, and towards the headstock, correct? So with each deeper pass, your tool will kickout a little farther along, even if your kicking out right on your way mark.

Does this cause problems for you?

Justin
 
Zebra13 said:
Jerry,

I do that exact thing. A little Sharpie mark on the ways...I find it easier than using an indicator. But if your feeding in with the compound, your tool is moving in, and toward the headstock, correct? So with each deeper pass, your tool will kickout a little farther along, even if your kicking out right on your way mark.

Does this cause problems for you?

Justin
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Justin, I just got up and don't have my trig hat on but you are only moving longitudinally about 0.025" to cut a 1/18 thread.
 
JerrySharrett said:
Justin, I just got up and don't have my trig hat on but you are only moving longitudinally about 0.025" to cut a 1/18 thread.
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Jerry,

I kinda thought the same thing. I remember reading somewhere that dialing in .003 on a compound set at 29.5 or 30 (I don't remember which one) will get you .001 actual in-feed on the Y axis. So total movement on the X axis due to a feed from the compound would be small, and would come in tiny increments as you fed in. The thread would get incremently longer as one made their passes, so if you hit your kick-out point, you really don't have to worry about thumping your tool. Does that sound about right?

Thanks for your help on this.

Justin
 
Zebra13 said:
Jerry,

I I remember reading somewhere that dialing in .003 on a compound set at 29.5 or 30 (I don't remember which one) will get you .001 actual in-feed on the Y axis. So total movement on the X axis Thanks for your help on this.

Justin
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About right Justin. Have you tried threading to a shoulder by using the felt-tip pen mark?

As a useless information point the left-right axis on a lathe is the Z-axis and the cross slide is the X-axis, a 2-axis lathe does not have a Y-axis. The reason? EIA standards which help set the standards for computer machine tools states that the principal axis for moving the cutting tool will be the Z-axis. The Z-axis on a vertical mill like a Bridgeport will be the quill, AND moving the tool into the workpiece with the knee will be the W-axis, now back to politics,.
 
JerrySharrett said:
About right Justin. Have you tried threading to a shoulder by using the felt-tip pen mark?

As a useless information point the left-right axis on a lathe is the Z-axis and the cross slide is the X-axis, a 2-axis lathe does not have a Y-axis. The reason? EIA standards which help set the standards for computer machine tools states that the principal axis for moving the cutting tool will be the Z-axis. The Z-axis on a vertical mill like a Bridgeport will be the quill, AND moving the tool into the workpiece with the knee will be the W-axis, now back to politics,.
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Jerry,

I thread towards the shoulder on all my barrels and use the mark on the way as my kick-out point. The last one I did, using carbide insert tooling, I spun at about 240 rpm's. The shoulder comes up quick, but it's not too difficult if your paying attention. Something that helped me was to have the tool about 6 inches from the barrel when I engaged the half-nuts. It gave me a bit of time to get my hand over to the cross-slide, get comfortable, pray that I don't run into the shoulder, etc.

I did note on the above threading job, that it seemed no matter how many passes I took at the same depth of cut, I would still get metal shavings coming off of the tool. Couldn't figger' that one out. But know, upon reading your post about lead screw and half nut slop, and not cutting a constant pitch thread, I think that is what was causing the metal shaving.

Your right on the axis thing. I was thinking mill axis when I typed up that post. I could never figger' out why it was different from lathe to mill...now I know.

Thanks,
Justin
 
For an 18 count thread what numbers can i engage on with the half nut? How about 16 count? I was thinking 16 is any number?
I cut some threads yesterday for the first time, and i must say it wasn't all that difficult. Actually i found it pretty simply. I threaded right up to the shoulder with out any troubles. Granted i was only running around 90 revs. I was using a carbide insert on a piece of scrap steel and the finish wasn't all that impressive? What do i need to do? Will the carbide insert be ok on the stainless at 90 RPM? Please advise. Thanks lee
 
Lee,

On MY lathe, if I am cutting even numbered threads, I can engage the half-nuts on any number. For odd numbered threads, I have to engage on the odd numbers. YOUR lathe may be different...I don't know. Give your owners manual a look.

My dad was taught, and he taught me, always engage on the same number...just to be safe.

When using carbide for threading (or turning), you have to get the RPM's up there to get the tool to work properly. That is why I mentioned threading at 240 RPM's in my above post. With HSS, you use lower RPM's.

Your use of scrap steel could be a contributing factor to un-impressive looking threads. Some steels machine better than others.

Justin
 
Justin
I dont have a manual with my machine. Im sure my father knows but he wasnt around yesterday. I did engage on the same number just to be safe and all was well. I just didnt know if i had to?? Yep all steel is different and i have no idea what type of steel i was cutting on yesterday? Thanks Lee
 
crowning tool

I also lipped bit with positive rake, I ground it from a round blank...I was wondering what Jackie use for his and if he happens to a pic
ture of it .
Thanks,
JCK
 
skeetlee said:
For an 18 count thread what numbers can i engage on with the half nut? s lee
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On some imports since they use some non-conventional thinking and have metric lead screws you need to figure it out yourself. That is what a machinist does, figures it out! The Industrial Revolution came about by early machinists figuring out how to make it....anything...make it. Just cut the first cut in a test piece, then back the tool off slightly and see what other places on the thread dial syncs with that cut.

On American machines, generally;

1) Even numbered threads engage at any mark.

2) odd numbers engage at any numbered mark ( ie 1,2,3,4 on the dial)

3) 1/2 pitch every other main division 1 & 3 , 2 & 4 (11 1/2 pipe for example)

4)other fractional pitch same division each time

5) Any multiple of the lead screw no dial needed, so if the lead screw is a 8 pitch you can cut a 8,16.24,32,40, or48 pitch thread with no thread dial.
 
JerrySharrett said:
Sorry, but no. I don't use them anymore.

Edit-
I need to clarify this. Before I retired one of my functions was called "tooling development". In that I looked into a lot of different types of cutting tools for many applications, milling, drilling, turning, etc. At that time we were using many thousands of carbide inserts ,mainly in turning and milling. We bought a few hundred thousands of dollars of this tooling each year. Valenite, Kennametal and Sandvik, mostly bid on these annual " contracts to supply". Sandvik had the best products for low stress metal removal. Low stress metal removal meant machining without pushback from the workpiece (like you would have taking a turning cut from thinwall Inconel tubing for example).

After I retired and using a tool room class lathe I very quickly found out that carbide insert tooling was not the best way to go on these low horsepower machines and machining light amounts of metal as in, for example, turning a tenon. After all it just takes 3 cuts to go from 1.210 to 1.06" and get a close tolerance measurement and good finish. Making a too-long story shorter, nothing wrong with Sandvik super sharp inserts, I just don't feel the need for them for barrel work.
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Thanks Jerry,

I wasn't looking to do barrel work either. I just wanted to be able to buy inserts. I have a few coro-mills, carbide insert drills, and their turbo mills with the profiled inserts that are insane price to get from DGI.

As of this year, Production tool is adding Sandvic / Coromant to their line of insert tooling. They have had in the past an agreement with Valenite / Walter, but both parties part ways (pun intended) this year. So the new 2012 Production tool catalog will have Sandvic coromant in it... Which is exciting since I get a healthy discount there.

Paul
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Thanks Paul, that sounds like an idea there. I don't know if I'll buy anywhere near enough to get decent pricing, but, if I don't and it's cheaper to change brands for new tools and inserts than it is to buy one or the other from sandvik, guess what I'll do!
 
Guys, I just don't follow the logic here. If we rely on reamers made of steel to form precision chambers, what
is wrong with HSS for crowning barrels. Sharpened correctly they will produce crowns equal to any carbide.
 
I prefer HSS hand ground bits for all work on barrels. It doesn't matter if it is flat, recessed, tapered of even radius cut. Sharply ground HSS with correct clearance works as good as anything.

This is a little off from Benchrest but here are some pics with a hand ground HSS tool cutting a radius crown on a muzzle brake. No polishing required after.

top of crowning tool
crowntooltop-0.jpg


bottom of crowning tool
crowntoolbottom-0.jpg


in the lathe
picture035-0.jpg


finish cut
picture036-0.jpg
 
I have some small carbide inserts for a little boring bar that have an 05 radius. They look like they will work quite well. any thoughts on the 05 radius insert? Do you pros think it will be sharp enough??? thanks fellas this has been a good read and i appreciate the participation. Lee

I was talking with Mr Warner of Warner tool company and he was telling me that a good cutting oil is as important as anything. He also says that he doesnt use HSS any more but that there isnt anything wrong with doing so. He also cleared up a big misconception about high tail stocks. I have always heard that most tail stocks are made to be a few thou high for wear of the ways. Mr Warner says thats BS He said a hobby type lather may it be in a private shop or a gunsmiths shop wont ever bee used enough to wear dawn a bed way. he says the tail stocks are high because the spindle will actually move when the machine gets warmed up and that after about 1hr of use the spindle will come into the proper height of the tail stock. he actually recommends turning o the lathe and letting it run for 1hr before using it, if you need the tail stock to be dead nuts true. I am sure i didnt explain all this properly but i think you will get the idea. He also said that some cheaper lathes are still a little to high even when they come in and if you want to surface grind the tail stock plate to leave it at least .002 high, and to never grind it dead nuts to a cold spindle. makes better since to me than a way getting worn out. Not to say a way couldn't get worn, but i wont ever wear one out. Mr Warner makes parts that have to stay with tolerances to the closest .000001. That i cant even imagine! I guess he builds some nice rifles to??
 
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skeetlee said:
I have some small carbide inserts for a little boring bar that have an 05 radius. They look like they will work quite well. any thoughts on the 05 radius insert? Do you pros think it will be sharp enough??? thanks fellas this has been a good read and i appreciate the participation. Lee
Click to expand...
G. Lee, it is not the nose radius per se that make many carbide inserts not suitable for crowning, instead, it is the edge sharpness. Since carbide inserts are made by powdered metallurgy process, meaning they start with a mixture (yes, mixture) of fine powder, then it is formed in "pill molds" (just like aspirin and Viagra) then these fragile shapes are stacked, by hand, into sintering ovens and cooked at about 3,000F.

This fragile "pill" ,if it were to have a sharp edge, much of that edge would sputter off, so the "pills" have rounded edges. It would require a separate operation to put a knife edge that would shave the metal off the crown area instead of bulldozing it off like a dull edge would. There are made, and you can buy, sharp edge carbide inserts (as well as sharp edge HSS inserts) but you will pay quite a bit more for them.

Just learn how to hand grind HSS or HSSCo tooling and get on with it. In a benchrest crown, you, for sure, don't want to use a grind like Dennis has shown above. While that design tool does make a neat looking, factory-like crown, it is not the best design for maximum accuracy.
 
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